WOOL FAT STEARINE 453 The saponification number is equal or almost equal to the acid number with .pomfied stearine and somewhat greater with distillation stearine The iodine number is barely a few units in good saponification stearines but may reach 15-30 m distillation stearines, owing to the presence of iso-oleic acid. sa1 WOOL FAT STEARINE This is the solid part of distiUed wool fat and consists of fatty acids and unsaponifiable substances (hydrocarbons, cholesterol). According to the consistency, it is distinguished as Soft stearine, melting below 45°, and Hard stearine or Wool fat wa%, melting above 45°. In general, these products have a waxy appearance, a yellow or brownish colour and a pronounced odour of wool fat, and they are soluble in hot alcohol and in ether, benzene or chloroform. When treated with cone, sulphuric acid, the chloroform solution turns red and afterwards violet with a green fluorescence (cholesterol). Analysis of wool fat stearine includes determinations of the melting point, acid number and content of unsaponifiable substances, as well as tests for added hydrocarbons (vaseline, paraffin wax) or resin. 1. Vaseline or Paraffin Wax.—The unsaponifiable substances from 50 grams of the stearine are boiled for 2 hours in a reflux apparatus with double their weight of acetic anhydride. The product is then washed repeatedly with boiling water until the reaction is neutral and in one part the acetyl number is determined (see p. 378). Another part (about 5 grams) is boiled with 50 c.c. of 90% alcohol, the liquid being filtered off and the residue boiled with 40 c.c. and then with 30 c.c. of 90% alcohol. Of the part insoluble in alcohol, which consists of hydrocarbons alone, the specific gravity, rotatory power (in benzene solution at about 20°) and iodine number are determined. 2. Resin.-.....-This is tested for as in wool fat oleine (see p. 451). * * * According to M'arcusson and Skopnik * and to Coen,2 wool fat stearines may melt between 40° and 65° ; they contain 56-90% of free acids (calculated as stearic acid) and 9-42% of unsaponifiable substances, which are brown, fluores- cent, pasty or semi-liquid masses with a faint aromatic odour and have the acetyl number about 25-37, the [a]D + 12° to + 30° and the iodine number 4.7-74. The portion of the unsaponifiable matter which does not combine with acetic anhydride (hydrocarbons free from higher alcohols) has 0=0-907- °'936> MB = + -'2° to -f- 21°, and iodine number =26-54. " 'Addition of extraneous hydrocarbons may be suspected when the acetyl number of the unsaponifiable substances is less than 25 and the portion of them not combinable with acetic anhydride has a specific gravity less than 0-9, [a]D less than -f 12° and an iodine number less than 26. 1 Zeilschr. angew, Chem., 1912, p. 2577. 2 Annali del Lab. cMm. centrale delle Gabelle, Vol. VI, p. 567- 10°, fat.